Ptrace System Calls
Ptrace System Calls [T1055.008]
Last updated
Ptrace System Calls [T1055.008]
Last updated
Name: Ptrace System Calls
ID: T1055.008
Tactics: ,
Technique:
Ptrace System Calls (T1055.008) is a sub-technique within the MITRE ATT&CK framework under the "Process Injection" technique (T1055). This method involves leveraging the Linux ptrace system call to manipulate and control the execution of other processes, potentially injecting malicious code or altering legitimate processes to evade detection and gain persistence. Attackers using ptrace can inspect, modify, or hijack process memory and execution flow, making it a powerful and stealthy method for privilege escalation, persistence, and evasion.
Ptrace (process trace) is a Linux system call commonly used by debuggers and diagnostic tools to observe and control the execution of another process. Attackers abuse ptrace to inject malicious code into running processes, read or modify memory, or alter execution flow.
Technical details and execution methods include:
Attaching to Processes:
Attackers first identify a suitable target process (often system processes or legitimate user applications).
Using the ptrace() system call with the PTRACE_ATTACH option, attackers attach their malicious process to the target, gaining control over its execution.
Memory Injection:
Once attached, attackers use ptrace() with options such as PTRACE_POKETEXT or PTRACE_POKEDATA to write malicious payloads directly into the memory space of the target process.
Attackers may inject shellcode, backdoors, or other malicious payloads directly into memory.
Execution Control:
Attackers can alter the execution context of the target process using PTRACE_SETREGS to modify CPU registers, redirecting execution flow to the injected code.
Once execution is redirected, attackers detach from the process (PTRACE_DETACH), allowing the compromised process to continue executing normally, masking their presence.
Stealth and Persistence:
By injecting into legitimate processes, attackers disguise malicious activities under trusted process names, evading detection by traditional monitoring tools.
Persistence can be achieved by periodically re-attaching and re-injecting code or by permanently modifying the process memory space.
Attackers typically employ ptrace system calls in various attack scenarios and stages, including:
Privilege Escalation:
Attackers attach to processes running with elevated privileges to escalate their own permissions.
Persistence and Stealth:
Malicious actors inject code into legitimate, long-running processes to maintain persistent access and evade detection.
Credential Harvesting:
Attackers attach to processes handling sensitive data, such as SSH daemons or browsers, to extract credentials or sensitive information directly from memory.
Defense Evasion:
By manipulating trusted processes, attackers avoid detection by endpoint protection solutions and security monitoring tools that rely on process reputation or signature-based detection.
Data Exfiltration:
Attackers can inject code into processes with network access to facilitate covert data exfiltration.
Detection of ptrace system call abuse involves a combination of monitoring, behavioral analysis, and proactive threat-hunting strategies. Detection methods and indicators include:
System Call Monitoring:
Monitor for abnormal usage of the ptrace() system call, especially when originating from unexpected processes or user accounts.
Tools such as auditd or Extended Berkeley Packet Filter (eBPF)-based monitoring solutions can log and alert on suspicious ptrace calls.
Process Behavior Analysis:
Detect unusual process attachments or modifications to memory segments of critical system processes.
Endpoint Detection and Response (EDR) solutions can identify anomalous process behaviors indicative of ptrace abuse.
File and Memory Integrity Monitoring:
Utilize tools like OSSEC, Tripwire, or AIDE to detect unexpected changes in memory regions or executable code segments of processes.
Indicators of Compromise (IoCs):
Presence of unexpected processes attaching to system-critical processes.
Unusual memory access patterns or process execution anomalies.
Suspicious ptrace-related audit logs or alerts from security monitoring tools.
Unexpected process crashes or instability due to malicious code injection.
Early detection of ptrace system call abuse is critical due to the following reasons and potential impacts:
Privilege Escalation:
Attackers leveraging ptrace can escalate privileges, gaining root-level access and full control over affected systems.
Persistence and Long-Term Compromise:
Injecting malicious code into legitimate processes allows attackers to maintain persistent and stealthy access, complicating remediation efforts.
Data Theft and Espionage:
Attackers can extract sensitive data directly from process memory, leading to data breaches, credential theft, intellectual property loss, and espionage.
System Instability and Downtime:
Malicious code injections can cause process instability or system crashes, leading to service disruptions, downtime, and operational impacts.
Evasion of Traditional Defenses:
Traditional antivirus and signature-based detection methods often fail to detect ptrace-based attacks, underscoring the importance of behavioral monitoring and proactive threat hunting.
Compliance and Regulatory Risks:
Undetected compromise can lead to breaches of sensitive data, resulting in regulatory non-compliance, legal penalties, and reputational damage.
Real-world examples of ptrace system call abuse by threat actors include:
Linux Malware and Rootkits:
Linux rootkits such as Azazel and Jynx2 leverage ptrace to inject malicious code into running processes, hiding their presence and evading detection.
Attackers have used ptrace-based rootkits to establish persistent backdoors and covertly exfiltrate data.
Credential Theft Campaigns:
Attackers have utilized ptrace to attach to SSH daemon processes (sshd) or browsers, extracting plaintext credentials directly from memory, leading to unauthorized access and lateral movement.
Advanced Persistent Threat (APT) Operations:
Nation-state threat actors have leveraged ptrace-based techniques in targeted attacks against Linux servers, injecting malicious payloads into legitimate processes for espionage and intelligence-gathering purposes.
Penetration Testing and Red Team Tools:
Open-source tools like injectso and custom scripts demonstrate how attackers can use ptrace to inject shared libraries or shellcode into running processes, simulating real-world attack scenarios.
Cryptocurrency Mining Malware:
Malicious actors have used ptrace system calls to inject cryptocurrency mining payloads into legitimate processes, stealthily consuming system resources for financial gain.
In each of these examples, attackers leveraged ptrace system calls to achieve stealth, persistence, privilege escalation, and evasion of traditional security controls, highlighting the critical importance of detection and mitigation strategies.